Urban energy systems in Tanzania

Urban energy systems in Tanzania A tale of three cities

Richard H. Hosier

This paper utilizes the detailed energy balance data developed as part of the Tanzania Urban Energy Project to analyse urban energy use in three Tanzanian cities. It first compares energyuse levels between the urban and rural areas. The evidence shows that urbanization involves a dramatic intensification of energy use. The energy-use patterns o f the three cities are then examined. The differences, which are notable, are largely consistent with the expectations derived from the theory of economic specialization across the urban hierarchy. Deviations from the expectations can be attributed to size, the natural environment and historical circumstances. Keywords: Urban energy;Urban hierarchy;Energybalance

The development of cities represents a fundamental change in human settlement patterns and entails a dramatic transformation of the physical environment. Industrial activity to supply employment and products for trade is important to the operation of cities, as is the production of an agricultural surplus in the city's hinterland. All of these activities involve a shift in the way that the urbanizing society uses energy: from human and animal power and biomass to electricity and petroleum fuels. Each city holds a unique position in this transformation: it hosts a different array of activities, relying upon a different mix of energy resources. These differences give each city a slightly different energy-use pattern which will, like a fingerprint, be unique. A large number of factors influence these patterns, perhaps the most important of which is the income level of the inhabitants of the city. Local economic activity, industrial development, settlement size and density, technoloThe author is with the Stockholm Environment Institute, G-29 Meyerson Hall, 210 S. 34th St, Philadelphia, PA 19104-6311, USA. 510

gical capabilities, local natural resource endowment, and the size of the hinterland served by the city are other factors influencing the city's energy-use patterns. As a city develops and grows, local economic activity intensifies, resulting in shifts in the ways in which energy is used. The size of early urban settlements was limited by endowments of one or more natural resources. The availability of fresh-water resources, food supplies and fuel resources placed upper limits on the growth of early urban settlements. On the African continent, for example, archaeological evidence suggests that the civilization centred on Great Zimbabwe collapsed in the latter 14th century due to the exhaustion of water, fuelwood supplies and pasturage. 1 In recent times, technological innovation has managed to postpone or stave off most physical or environmental limitations on urban growth. According to simulations based on general equilibrium models, fuel-resource shortages will do little to limit the growth of cities in developing countries. Evidence to date demonstrates that technology has continued to push back the limits to urban growth. 2 Viewed in this light, the limits to urban growth are not set by the natural environment, but rather are created by the failure of humans to bring technology to bear on urban problems. Even the extreme problems encountered in megacities appear to be manageable with the application of sufficient capital and technology. 3 Harnessing technology imposes certain costs, and unless these costs are met, the technology needed to manage urban growth and provide a reasonable quality of urban life will not be forthcoming. Both private and public investment are necessary to provide for urban growth. While private investment creates employment opportunities in industry and commerce, public sector investment supports private employment opportunities primarily through infrastructural investments. 4 Without this investment, cities are nothing but massive villages 0301-4215/93/050510-14 ~ 1993 Butterworth-Heinemann/td

Urban energy systems in Tanzania

with none of the services normally associated with urban life. 5 Tanzanian cities suffer from low levels of investment by both the private and public sectors. 6 Private sector investment has been discouraged by the politicoeconomic atmosphere of post-independence Tanzania. The public sector's ability to invest in the urban areas was destroyed through the abolition of urban councils in the early 1970s. Even though urban councils have since been reinstated, their ability to collect revenue for the construction and maintenance of infrastructure has never fully recovered. These influences, compounded by a poor record of economic growth, have caused Tanzanian cities to outgrow the infrastructure inherited at independence. The investment necessary to keep employment growth, service provision and infrastructure at reasonable levels relative to the magnitude of urban population has not been forthcoming. In the energy sector, infrastructural investment refers most clearly to investments in electricity generation and distribution and petroleum transport, storage and distribution. A weak energy infrastructure is indicated by a limited use of modern fuels for most urban energy needs. The heavy reliance on traditional fuels for urban energy needs reflects low income levels, the limited nature of energy infrastructure and erratic supplies of modern fuels. This paper investigates the relationship between energy and urbanization using the data from the three Tanzanian cities ( D a r e s Salaam, Mbeya and Shinyanga) gathered as part of the Tanzania Urban Energy and Environment Project. It examines the energy-use patterns of these three cities and identifies differences arising from size or scale, sectoral composition and vegetation cover. A comparison of the different energy-use patterns on a per capita basis demonstrates that inhabitants in all three cities utilize more petroleum fuel, charcoal and electricity per capita than do rural inhabitants. Rural inhabitants, on the other hand, account for an extremely high consumption of biomass fuels, particularly firewood. As urbanization continues, modern fuels and charcoal will increase their share in the national energy balance. Of the three cities examined, per capita energy use is highest in Mbeya, reflecting the heavy use of firewood and petroleum fuels in that city. This reliance on firewood is attributable to the extensive area of eucalyptus plantations located within the town's boundaries. By contrast, a larger share of total energy use in Shinyanga is made up of charcoal, as a result of the extreme shortage of firewood in the vicinity of the town. The use of modern fuels per

ENERGY POLICY May 1993

capita appears to increase with city size as a reflection of the greater concentration of industrial and commercial activity in the larger cities. This trend is countered by decreasing per capita consumption of traditional fuels in the larger cities, again reflecting a decline in the dominance of the local economy of the household sector, and the increasing importance of industry and commerce. Continued urban growth will drive future energy demand, increasing overall resource requirements. The nature of the shifts in energy demand patterns will depend upon the extent to which industrialization drives urbanization. Without growth in the industrial sector, energy demand growth will entail only an increased intensity of traditional fuel use. As greater industrialization occurs, future energy demand growth will shift increasingly toward modern fuels away from traditional fuels.

The city as an energy system Although a city can be described metaphorically as an organism, such comparisons are easily strained. Even attempts to describe a city as a unified system quickly encounter boundary problems: where does the city end and the hinterland begin? Are activities which supply urban goods from the hinterland part of the system of the city? How should the supply of goods from the hinterland of other cities be treated? Questions of this type typically complicate and confuse any discussion of the city as a system. As a result, some simplifications are needed if the discussion is to extend beyond the definitional stages. In the following analysis, the discussion focuses on the energy which is used within the political boundaries of the city. The fuel-supply chain will not be followed all the way back to the ultimate supply source for fossil fuels and electricity. For firewood and charcoal, the ultimate supply has been traced to the location of the source, since this lies within the agricultural hinterland of the city. Although this procedure does much to simplify the following discussion, boundary problems still arise. For example, the quantity of kerosene, diesel and petrol sold within a region's boundaries is generally known; the quantity actually utilized within the region's boundaries is not. This problem is particularly acute when analysing the quantity of kerosene used within a city and the quantity used in the rural hinterland of a city. It also appears when the petroleum fuels used for intraurban transport are distinguished from the liquid fuels used for interurban and rural-urban transport. Although these transport fuels are not consumed within the city p er se, their consumption

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Urban energy systems in Tanzania

does reflect how important the city is as part of the national urban system. The inclusion of all transport fuels distributed within a city as part of the city's consumption is probably justified: the inclusion of all kerosene is more problematic. At present, no satisfactory solution to this accounting problem exists, so all fuels disseminated to a particular city will be considered as part of its consumption. Despite these problems, other authors have utilized the model of a city as a system to examine various energy and environmental impacts of urban life. 7 The ecology of cities as diverse as Hong Kong, Nakuru, Dhaka and Jakarta have been examined to highlight the flow of food, energy and other materials passing through them.8 Although these enquiries focus on different cities and different components of the environment, they reflect a concern for the sustainability of urbanization. All of these cities have demonstrated increasing per capita requirements for both inanimate energy resources and food supplies as the development process has intensified. Large increases in energy are required to fuel not only increases in industrial production, transport and household subsistence needs but also for the increasing energy requirements of housing, service provision and luxury consumption. A cross-sectional comparison of energy-use patterns in different cities has demonstrated that the need for increased transport and industrial development drives this process of energy intensification (both per capita and per unit GDP) as urbanization proceeds. 9 The urban settlement pattern of a particular city goes a long way toward determining its transport energy requirements. In general, lower settlement density means greater transport energy consumption. To date, factors other than energy have dominated urban planning activities. Few, if any, cities have been able to consciously control energy use through planning either the location of new settlements or settlement density. 10 These studies of cities as systems have clearly demonstrated the intensification of energy use as urbanization continues and the development process proceeds. However, none of the studies has examined the energy requirements of several cities in the same country to determine how urban energy use differs according to location in the urban hierarchy, local ecology and level of development. This paper's contribution lies in assembling and comparing the energy balances for three cities in Tanzania for the same year. It is anticipated that this approach will yield a greater understanding of the relationship between energy and urbanization. The next section summarizes the methodology used in the analysis of

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energy use across the urban hierarchy. The following sections then use the assembled data to discuss different aspects of the energy consumption patterns of the three case study cities.

Methodology This paper analyses data collected as part of the Tanzania Urban Energy and Environment project. These data include energy utilization data for the household, industry, transport, commercial and informal sectors of the economy. 11 The supply chain for fuelwood and charcoal was then traced to the point of production in order to ascertain information about woodfuel markets and production information. The data were then synthesized into a single energy balance for each of the three cities selected as case studies. 12 The fuel-supply figures for petroleum fuels and electricity were used to adjust the energy consumption data for each city to the known total consumption of each fuel for 1990. In this way the detailed end-use consumption of each case study city was established from interviews and surveys and was then calibrated according to the known total consumption. The following sections use these results to analyse the base year energy accounts for each of the three cities. In particular, questions about how urban energy use in Tanzania differs from rural energy use, and about how urban energy use differs between the three cities under examination, are addressed. The differences between the energy-use patterns of the three cities are ascribed to urban size, position in the urban hierarchy, local ecology and history. The discussion is intended to provide a key for understanding the differences between urban energy use in other African countries and elsewhere. It demonstrates that urban energy use is neither uniform nor monolithic within a country, just as previous work has demonstrated that rural energy-use patterns vary by location within a specific country. A range of urban energy-use patterns may exist, depending upon the population of a city and its position within the urban hierarchy. As a result, policies which are beneficial in one urban area may be inappropriate in another.

Present patterns of urban energy use The estimated end-use energy consumption for each of the three cities is listed in the top half of Table 1, along with the total national energy consumption estimated for the whole of Tanzania. D a r e s Salaam's total gross energy consumption is 6.1 times

ENERGY POLICY May 1993

Urban energy systems in Tanzania Table 1. Magnitude of end-use energy consumption. Dar es Salaam Absolute energy consumption (GJ × 103) Electricity 2 240 Gasoline 1 490 Kerosene 940 Diesel 4 280 Residual/fuel oil 4 030 LPG 60 Firewood 2 010 Charcoal 7 280 Crop residues 210 Dung Total 22 520 Population 1988 1 214 251 1978-88 growth rate (%) 4.56 Estimated 1990 population 1 330 310 Per capita energy consumption (GJ) Electricity 1.683 Gasoline 1.120 Kerosene 0.707 Diesel 3.217 Residual/fuel oil 3.029 LPG 0.045 Firewood 1.511 Charcoal 5.472 Crop residues 0.158 Dung Total 16.942

Mbeya City

Rural areas 150 40 2 580 410 810

Tanzania (total)

1 080 820 70 3 720

64 56 107 88 4 0.3 93 400 7 10 828

469 6 37 517

131 864 5.58 146 991

46 904 8.66 55 380

19 721 804 2.8 20 841 687

22 533 758 2.8 23 813 315

1.020 1.020 1.429 6.054 2.313 7.347 5.578 0.476 25.237

1.156 1.010 1.932 1.589 0.072 0.005 1.679 7.223 0.126 0.181 14.97

0.007 0.002 0.124 0.020 0.039 22.515 0.288 1.781 24.78

0.202 (}.206 0.287 0.687 0.279 0.006 20.160 1.039 1.590 0.005 24.46

150 150 210 890 340

that of Mbeya and 27.2 times that of Shinyanga. The former ratio is slightly less than the ratio of the urban populations of Dar es Salaam and Mbeya (9.1), but the latter is greater than the ratio between the ratios of Dar es Salaam and Shinyanga (24.0). In general, total urban energy consumption is roughly proportional to a city's population. In Mbeya the sizable deviation between the population and energy consumption ratios is attributable to the large share of firewood in its total energy consumption. However, difficulties in comparing the absolute magnitude of gross energy figures dictates that the following comparisons draw upon per capita and percentage figures to add greater clarity to the discussion. Each of the three cities comprises a small portion of total national energy consumption. Even Dar es Salaam, large as it is, accounts for less than 4% of total national energy consumption. Rural fuelwood use still accounts for 78.6% of total national energy consumption. However, consumption in Dar es Salaam accounts for over 30% of the national petroleum and electricity consumption, 13 and over 27% of total national charcoal consumption. With only about 5% of the national population, Dar es Salaam accounts for the consumption of an inordinately large share of modern fuel and charcoal. As it is the largest centre of industrial and commercial activity, this is to be expected. However, the three subsectors

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Shinyanga City

4 4 6 16 6

250 010 120

480 24 37

120

596

810 910 840 360 640 140 090 760 870 110 890

considered to be entirely rural - rural households, rural industry and agriculture - account for nearly 90% of total estimated national energy consumption. The rural population (accounting for 87.5% of the estimated 1990 population) and its energy consumption (largely in the form of firewood) dominate the national energy balance. The next subsection examines the differences between energy-use patterns of settlements located in urban and rural locations; the second examines differences attributable to position in the urban hierarchy; and the third examines those attributable to local ecology and history.

Energy impacts of urbanization The lower half of Table 1 provides annual estimates of energy consumption per capita by fuel type for each city and the nation as a whole for 1990. Of the three case study cities, Mbeya is the most energy intensive, requiring about 25 GJ per person per year, as opposed to 14.6 GJ per person per year for Shinyanga, 16.9 GJ per person per year for D a r e s Salaam, and 24.8 GJ per person in the rural areas. Clearly, the difference between these overall numbers is attributable to the large quantity of firewood used in Mbeya and the relatively low efficiency of its use. Mbeya's energy intensity more closely resembles that of the country as a whole, and in

513

Urban energy systems in Tanzania 30

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Figure 1. Energy use per capita: urban versus rural. particular, the rural areas, because of this heavy reliance on firewood. For all modern fuels combined (electricity plus petroleum fuels), Mbeya is also the most energy intensive city, consuming an average of 11.91 GJ per inhabitant. This high consumption reflects the large flow of liquid fuels through Mbeya to the railway. D a r e s Salaam is the second most modern-fuel intensive city (9.9 GJ per capita) and Shinyanga is the least consumptive of modern fuels (5.7 GJ per capita). These figures are all higher than the estimates for the rural areas (0.228 GJ per capita) and the nation as a whole (2.26 GJ per capita), reflecting the concentration of modern-fuel use in the cities. Modern fuels are consumed mostly in the urban areas, reflecting the industrial needs of the cities. Both settlement density and the density of industrial and road transport activities are higher in the cities. For traditional biomass fuels, D a r e s Salaam residents demonstrate the lowest per capita consumption of traditional fuels (7.1 GJ per capita), followed by Shinyanga (9.2 GJ per capita) and Mbeya (13.4 GJ per capita). These figures are dwarfed by the per capita consumption of traditional fuels in the rural areas (24.6 GJ per capita) and the nation as a whole (22.8 GJ per capita). The simple averages reveal two facts. First, Tanzania is a rural country, with about 85% of the population living in rural areas. Second, this rural population is largely dependent upon traditional, biomass fuels. While the industrial energy needs of the nation are largely met through modern, commmercial fuels, subsistence needs continue to be met through traditional fuels, either commercially supplied or freely gathered. From this preliminary discussion it is apparent that the annual energy consumption of an average

514

rural inhabitant is greater than that of an average inhabitant of either D a r e s Salaam or Shinyanga. The situation is represented by the histogram in Figure 1. Modern fuel use, largely responsible for the industrial energy needs of the country, is heavily biased towards the urban areas, as is charcoal use. Firewood use, accounting for about 80% of national end-use energy consumption, serves the predominantly subsistence needs of the rural areas. Urban dwellers make use of a greater quantity of useful energy as the efficiency of use for modern fuels exceeds that for firewood. 14 Urban life requires that inanimate sources of energy be harnessed to perform a greater quantity of work. Final energy consumption patterns may differ from primary energy-use patterns as a significant quantity of energy lost in conversion is not included in these final consumption estimates. The impression obtained from examining the final consumption of end-use fuels differs from that obtained from an examination of the resource requirements required to produce those fuels. The entire Tanzanian energy system is dependent upon three primary fuels: biomass, hydropower and petroleum. Figure 2 presents estimates of the quantity of the three primary resources required to produce the end-use fuels. 15 On average, urban residents consume more primary energy resources than do rural residents. Not surprisingly, increasing urbanization results in increasing overall resource requirements per capita. Urbanization represents an intensification of resource use, just as it requires an increase in useful energy consumption. Urbanization is an expensive process, not only when measured in terms of physical resources, but also when measured in terms of financial flows.

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Urban energy systems in Tanzania 60

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Figure 2. Energy resource use per capita: urban versus rural. Figure 3 estimates the economic cost of meeting the average energy-consumption profiles presented above.~6 These estimates clearly show that the economic costs of supplying energy for an urban resident are far greater than the costs of supplying a rural resident. This is due to the fact that rural residents require a smaller quantity of commercial energy than urban residents and that firewood, the dominant fuel in the rural energy profile, is comparatively cheap in rural areas. As a result, the economic costs of supplying the energy needs of a rural resident are nearly one-third those of supplying an urban resident. From the perspective of the nation as a whole, one resident migrating to the city results in a tripling of the economic costs of supplying that person's energy needs. Urban migration results in a

dramatic increase in the cost to the economy of meeting national energy consumption. This increase is accounted for by the increased use of petroleum fuels and electricity for transport, industry and commerce, as well as the increased likelihood of charcoal, petroleum fuels or electricity being used to meet subsistence (household) energy needs. Although Figure 3 lists the full economic costs of supplying energy, the financial cost of urban and rural energy supplies is the only cost commonly met. These out of pocket costs are a small fraction of the economic value of the resource in the case of gathered firewood and heavily subsidized electricity. The financial costs may range from as little as 4% to as much as 90% of the economic costs of supply. Clearly only a small fraction of the true economic

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Urban energy systems in Tanzania

costs of the energy supply are met by the users. 17 The remainder of the economic costs are either not met, or are met by government subsidies, the depreciation of the national energy system or the degradation of the national environment. For future urbanization to be sustainable, the full economic costs of the energy required for urbanization will have to be met. The figures presented so far demonstrate that the physical energy requirements of an average rural inhabitant are slightly higher than those of an urban inhabitant, but only when these are measured in terms of end-use fuel requirements. In terms of the resources needed to produce those end-use fuels, all of the urban areas studied demonstrated higher per capita resource requirements than did rural Tanzania. From this perspective, the process of urbanization is accompanied by an intensification of resource use, as more liquid fuels, hydropower and woodfuels are needed for the increased industrial, commercial and transport activities. Even household subsistence needs are met in a more resource-intensive manner, with charcoal replacing firewood as the dominant fuel in the household energy sector. Urbanization also leads to a more expensive energy system as the costs of providing the energy resources needed by the average urban dweller are several times higher than the costs of supplying the average rural dweller. Financial and economic costs are incurred as the household is no longer able to supply its own energy needs through subsistence activities. Unfortunately, the full economic costs of supplying the necessary energy supplies have rarely been met. Rather, the users pay only the financial costs, with the difference between the two being absorbed by the government, in the case of electricity, or the environment, in the case of fuelwood. The energy related expense of urbanization will be increasingly apparent as a larger share of the economic costs of urban energy supplies begins to be met by consumers.

Energy-use variations across the urban hierarchy The preceding section focused on the differences between the overall energy-use patterns of rural and urban Tanzania. This section examines interurban patterns in order to identify the differences in the energy needs of cities at different levels of the urban hierarchy. The number of businesses and industries found in an urban centre do not remain in fixed proportion to the size of the settlement. Rather, because specialized businesses and industries have threshold sizes which can only be achieved given a sufficiently large urban market and supporting hinterland areas, primate cities will contain a greater

516

variety of commercial and industrial establishments on a per capita basis that will lower-order market centres. In a similar manner, secondary cities will contain the next largest number and range of establishments and so on down the urban hierarchy. The implications of this economic specialization for energy use are relatively straightforward. In larger cities and towns, the industrial and commercial sectors comprise a larger share of total economic activity, and so the fuels used in business and industry will make up a larger fraction of the total energy budget. Households can be expected to make up a smaller share of total energy use in the larger cities and towns, as household production accounts for a smaller share of total production. Households in larger cities purchase a larger share of the goods they consume. In addition, not only is the servicing of regional transport needs more important in higher order cities but, given their larger physical size, intraurban transport plays a more important role as well. In general, then, urban transport can be expected to comprise a larger share of the urban energy budget in higher order cities. The sectoral shares of the urban and rural energy budgets for the case study cities are presented in Table 2 and Figure 4. With several exceptions noted below, these estimates support the hypothesized relationships presented above. In particular, the household sector's share of total energy consumption decreases with moves from the rural areas to increasingly larger cities. It is least significant in Dar es Salaam. Industry's share of total energy use decreases slightly from the primate city to the secondary city to the tertiary city in the expected manner. While transport's share decreases from the largest to the smallest city, transport represents a slightly larger share of energy use in Mbeya than in D a r e s Salaam. This exception can be attributed to the large quantity of liquid fuels which are shipped to Mbeya to refuel the T A Z A R A railway and service the southern agricultural hinterlands. In general, while household energy use decreases as a share of total energy consumption with movements up the urban hierarchy, both industry and transport energy use increase in importance. These findings are consistent with predictions based upon an understanding of economic specialization and agglomeration. 18 The exceptions to the predictions are relatively minor. The first is the relatively large fraction of the rural energy budget made up by the rural industrial sector (13.2%). This is higher than the comparable figure for either Mbeya (11.9%) or Shinyanga (5.2%) and rivals the estimate for Dar es Salaam (13.9%). In a similar manner, the commercial sector

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Urban energy systems in Tanzania

Table 2. Sectorai composition of end-use energy consumption (%).

Households Informal sector Commerce Industry Transport Urban services Agriculture Total

Dar es Salaam

Mbeya City

Shinyanga City

Rural areas

Tanzania total

53.53 2.05 1.77 13.93 27,88 0.83 100.0

58.00 1.98 0.57 11.93 27.51 0.02 100.0

73.39 2.94 4.61 5.19 13.76 0.11 100.0

83.06 13.19 3.75 100.0

77,34 0.55 0.18 15.00 3.65 0.03 3.25 100.00

Table 3. Percentage composition of end-use energy consumption (%).a

Electricity Gasoline Kerosene Diesel Residual/fuel oil LPG Firewood Charcoal Crop residues Dung Total

Dar es Salaam

Mbeya City

Shinyanga City

Rural areas

Tanzania (total)

9.95 6.60 4.15 18.99 17.88 0.25 8.92 32.33 0.93 100.00

4.11 4.02 5.66 23.98 9.25 0.04 29.09 22.09 1.76 100.00

7.77 6.76 12.97 10.58 0.43 0.03 11.22 48.26 0.78 1.18 100.00

0,03 0.01 0.50 0.08 0.16 90.74 1.16 7.18 100.00

0.81 0.82 1.15 2.74 1.11 0.02 80.43 4.14 6.34 0.02 100.00

aBecause of rounding errors, the percentages may not exactly total 100%. Coal and coke (comprising about 0.1% of national consumption) have been omitted.

in Shinyanga (4.6%) accounts for a much larger portion of the urban energy budget than it does in either Mbeya (0.6%) or Dar es Salaam (1.8%). Although industry tends to be more important in larger cities, it is likely that these differences in commercial sector consumption also correspond to definitional difficulties. Both discrepancies can be rectified by combining the informal sector, commercial and industrial energy use in all three cities, as the distinctions between formal and informal indus-

try and industry and commerce are often blurred with microlevel data. This process yields the following numbers for commerce-industry: Dar es Salaam (17.8%); Mbeya (14.5%); Shinyanga (12.7%); and rural (13.2%). These corrected data conform more closely to the anticipated values.19 These sectoral differences result in different fuel mixes for the urban energy budgets. These fuel mixes are presented in Table 3 and Figure 5, and demonstrate the increasing importance of petroleum

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Urban energy systems in Tanzania 1.0

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Figure 5. Energy consumption by fuel: fraction of total. fuels to the energy budgets of the larger cities. Petroleum fuels account for the largest share of the overall energy budget in Dares Salaam (43.0%). In Mbeya petroleum fuels are also very important, constituting nearly 43% of total energy use. In Shinyanga and the rural areas, petroleum fuels constitute 31% and 6% of total energy use respectively. 2° Industry and transport are far more important in the energy budgets of the larger cities. However, diesel accounts for nearly 24% of Mbeya's energy use, an anomaly attributable to the railway depot. The importance of electricity also appears to increase with urban size. However, it is not clear whether the fact that electricity is more important in Shinyanga than in Mbeya is attributable to the underdeveloped infrastructure network of the latter or to an unusually well developed electricity network in the former, given its size. 21 The electricity supply system developed by the Williamson Diamond mine (Mwadui) may have given Shinyanga a more advanced electricity network than would have been justified solely on the basis of its importance as a population centre. Although firewood represents a large share of total energy utilization in Mbeya, the fraction of the total energy budget made up by biomass fuels (firewood, charcoal, crop residues and dung) increases steadily from D a r e s Salaam (42.2%) to Mbeya (52.9%) to Shinyanga (61.4%) and the rural areas generally (90.9%). Charcoal alone accounts for nearly 50% of the energy consumed in Shinyanga. This can be attributed both to the increasing utilization of modern fuels and the decreasing fraction of consumption attributed to the household sector and traditional fuels as size of the urban settlement

518

increases. It also reflects a shift toward charcoal and modern fuels in the larger cities. The economic geography of the urban hierarchy provides an appropriate framework for explanation of these results. Economic specialization and localization means that the larger a city, the greater the number of enterprises located there, the greater the range of goods which can be purchased, and the more complex the energy balance. In this case, the largest city, D a r e s Salaam, demonstrates that industrial, commercial and transport sector consumption account for the highest fraction of its energy use. The resulting fuel mix contains a higher fraction of modern fuels, electricity and petroleum fuels. Household consumption plays a more important role in the smaller urban and rural centres, and the resulting energy balance is biased toward traditional biomass fuels. Thus, with several minor exceptions, the three cities under examination reveal energy balances that are consistent with what would be expected on the basis of simple market-centre geography. Additional factors may influence the differences between intercity energy use for the cities examined. For example, D a r e s Salaam has a larger number of both public organizations and street lights than do the other two cities. Pumping water in Dar es Salaam requires much more energy than in either Mbeya or Shinyanga, as it must come from over 60 km away. However, energy use for urban services in Shinyanga (940 GJ or 0.02 GJ per capita) is larger in both absolute and relative terms than energy use for urban services in Mbeya (600 GJ or 0.0045 GJ per capita), due largely again to the difficulties of pumping water into Shinyanga. 22

ENERGY POLICY May 1993

Urban energy systems in Tanzania Variations due to local ecology and history

The differences outlined in the previous section are attributable largely to differences in the economic structure and population of the three cities under examination. However, not all the differences in the energy budgets of these three cities are attributable to size and position within the urban hierarchy. This section examines some of these exceptions which can only be explained on the basis of local ecology and history. The importance of local ecology and history are most obvious in the case of firewood use in Mbeya, where the mix of fuels used includes more firewood than would be anticipated on the basis of its population and position in the urban hierarchy. In the years preceding independence, Mbeya was a small town that provided a centre for agricultural and forestry activities in the southern highlands. As a result, most of the indigenous woodlands in the area were cleared to make way either for cultivation or eucalyptus plantations and woodlots (located even within city limits). These woodlots and plantations continue to provide a large share of the energy used by the household sectorY As a result of this historical influence, firewood is considerably more important in the energy budget of Mbeya than it is in the other two cities examined. Even without this relatively plentiful local supply, firewood consumption within Mbeya city limits might be expected to be higher than that in any of the other three cities due to Mbeya's altitude. A significant quantity of the firewood used in Mbeya goes for space heating made necessary by the relatively low temperatures. Thus, local environmental conditions have led to a greater demand for firewood for heating. Historical circumstances have served to make firewood easily accessible. The net result is that large quantities of firewood are consumed in Mbeya. In Shinyanga, the local ecology is arid and woody biomass vegetation has been scarce for a long time. It would generally be expected that the consumption of firewood (especially gathered firewood) would increase in smaller urban areas, as the population engages in more subsistence activities. However, Shinyanga has long been considered to be one of the most wood-short areas in Tanzania. 24 Surprisingly, charcoal use per capita is heavier in Shinyanga than it is in the other two cities, due to the local shortage of firewood which makes the importation of charcoal necessary. Despite the fact that charcoal is transported further into Shinyanga than into either Dar es Salaam or Mbeya, and is therefore more expensive, 25 charcoal consumption per capita is higher. As a result, Shinyanga's energy consumption

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per capita places the greatest drain on woody biomass resources of any of the three cities, even though the city is located in an environmentally poor region. Despite the relative scarcity of firewood, activities such as traditional beer brewing, which uses large quantities of firewood, are probably more common in Shinyanga than in the other two cities. In addition, only in Shinyanga was dung found to play an important role in the energy budget, due not only to the shortage of firewood, but also to the importance of livestock to the local economy. Cultural history and the low potential productivity of its surroundings have combined to make Shinyanga a wood-short city. Dung and charcoal are heavily used to make up the gap left by the localized woodfuel shortage. Local ecology and history combine with city size and economic specialization to give these three cities different energy-use patterns. As elaborated earlier, the economic costs of supplying the energy necessary to support one person are lowest in the rural areas. Figure 3 indicates that Mbeya has the most expensive urban energy system of the three cities. On the basis of these figures, Dares Salaam does not appear to face significant diseconomies of scale with respect to energy supply. If any of these cities faces energy diseconomies of scale, it would appear to be Mbeya, which has the weakest urban infrastructure measured in terms of electricity supply, water supply and road networkfl6 This weak infrastructure reflects both the rapid growth experienced in Mbeya over the past two decades, and the failure to invest in urban public works. Although Mbeya has grown too large to rely on traditional, rural technologies, it has not yet made the investment necessary to make use of the more sophisticated resource management technologies available to cities with a well developed infrastructure.

Toward an understanding of urban energy systems The data presented in the preceding pages illustrate differences in the energy-use patterns of the three cities examined as part of this project. Those differences were ascribed to position in the urban hierarchy, size, local ecology and history. This section summarizes the identified differences, points to their relevance for other cities and countries, and discusses how these patterns might change with further urban growth and development. Turning first to the question of size, urban settlements in Tanzania now consume far more of both modern fuels and charcoal than their rural counter-

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parts. Although rural dwellers consume more gross energy per capita than do urban dwellers (Figure 1), their consumption achieves less useful output as they rely heavily upon firewood which is used at low levels of efficiency. Both modern fuels and charcoal are used at greater end-use efficiencies and therefore provide greater useful energy. Particularly if the wood energy lost in the charcoal conversion process is included, urban dwellers would appear to lead a more energy-resource intensive lifestyle than rural dwellers (Figure 2). Within the urban areas themselves, the physical magnitude of a city appears to influence directly the quantity of energy consumed per inhabitant. The larger the physical size of a city, the greater the energy requirements for intracity transport. But physical size and transport influence other energy consumption habits. Also tied into transport economies is the propensity to utilize traditional fuels (firewood) and commercial fuels (charcoal). In larger cities, inhabitants will rely upon commercial fuels (including charcoal) as it is uneconomical to transport firewood long distances. In smaller cities, households can make use of traditional fuels (firewood) as the necessary transport distances are not that great. This might lead to the assumption that energy supplies would be more expensive in the larger cities, but this is not always the case. Of the three cities examined, the price of charcoal is highest in Shinyanga, while the price of fuelwood is highest in Mbeya. Both of these findings run counter to expectations. Although the cost of the per capita energy profiles for these three cities does not reflect the anticipated price variations (Figure 3), consumption patterns appear to play a large part in determining the total energy cost per inhabitant. However, the cost of supplying the per capita energy profile for all three cities greatly exceeds the costs of supplying those individuals still living in the rural areas. Position in the urban hierarchy appears to have a direct influence on the sectoral mix of energy consumption. In the rural areas, the household sector is the dominant energy user, followed by rural industry (tobacco drying and beer brewing in this case) and agriculture (Figure 4). While the household sector tends to decrease in importance, the role of industry and transport tends to increase with movements up the urban hierarchy; transport and industry make up nearly 50% of the energy profile of D a r e s Salaam, the primate city, but combine to provide only about 40% and 15% of the energy profiles of Mbeya and Shinyanga respectively. The importance of industrial specialization and transport services at the higher levels of urban hierarchy dictates that these two

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sectors will be increasingly important. In a similar manner, the energy requirements for the provision of urban services also increases with movements to higher levels of the urban hierarchy. Viewed from the perspective of fuel mix (Figure 5), electricity and petroleum fuels are more important in primate cities than in secondary or tertiary cities, reflecting the greater importance of industrial and transport sectors. The roles played by size and urban hierarchical position in determining urban energy use might be anticipated to transfer to other countries. Relative to the energy balances of smaller order cities, a primate city's energy balance will show a greater use of petroleum fuels for transport, given the larger size of the city and its role in servicing smaller urban centres. It will also be more heavily dependent upon electricity to serve the city's more specialized industrial and commercial sectors. The household sector's role will be more important in the smaller cities and towns, and largest in rural areas where subsistence production of many goods prevails. Households in larger cities will show a tendency to use charcoal instead of woodfuel due to transport economies. An important consideration is that while the energy use per capita may be lower than in smaller cities, the pressure placed upon forest resources per person will necessarily be greater. The results of this study reinforce those found for Nakuru, a secondary city in Kenya. 27 The secondary city was found to place greater pressure per capita on the surrounding forest resources than the primate city, Nairobi. Not surprisingly, the consumption of petroleum fuels and electricity per capita was much lower in Nakuru than in Nairobi. In a similar way, Mbeya's firewood and charcoal consumption per capita combine to give a higher level of consumption of biomass fuels than either D a r e s Salaam or Shinyanga. However, when the conversion of firewood into charcoal is taken into consideration, Shinyanga places the greatest drain per capita on overall forest resources. In contrast to Nakuru, however, Mbeya inhabitants actually make greater use of petroleum fuels per capita than do those of D a r e s Salaam. Natural environmental conditions, such as altitude or rainfall, or historical circumstances, such as the location of a university or industry, may serve to shift urban energy consumption patterns from their expected levels. Using the cases presented, Mbeya's heavier per capita use of petroleum transport fuels results from the strategic consideration that placed the last major railway depot in the T A Z A R A railway line on the Tanzania side of the border in

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Urban energy systems in Tanzania

Mbeya. Ecological circumstances, such as Shinyanga's location in a semi-arid steppe and D a r e s Salaam's location on a coastal plain, also influence energy-use patterns. In addition, historical circumstances and ecological conditions may interact to influence expected patterns. For example, Mbeya's population depends heavily upon firewood because a large area of eucalyptus plantations are located in the immediate vicinity of town. The plantations were located through the efforts of the colonial forest service, which chose the site because of its favourable characteristics for planting trees. Mbeya's dependence upon firewood for its energy needs thus results from historical circumstances which have reinforced local ecological conditions. Future urban growth may alter current relationships between energy use and urban size. If urban growth resembles that of the recent past in that it occurs without substantial industrialization, then the energy consumption of all cities in Tanzania should increase in magnitude, with relatively few shifts toward modern fuels. The consumption of woodfuel resources will probably increase in absolute magnitude, reflecting the tendency for households and businesses in larger towns to rely on charcoal in place of firewood. Petroleum fuel consumption per capita may increase slightly, reflecting the relatively greater need for transport. However, to the extent that future urban growth is fired by renewed industrialization, both electricity and petroleum consumption per capita would be expected to increase dramatically, as both are essential ingredients for industrial growth. Future urban growth is unlikely to result in dramatic shifts in the urban hierarchy. Dares Salaam is not likely to be replaced as Tanzania's primate city. Notwithstanding, there is a possibility that certain tertiary cities may grow more rapidly than others, evolving into secondary cities more quickly than would be anticipated on the basis of historical trends. Mbeya provides an example of this type of explosive growth. During the late 1950s and early 1960s virtually no one would have expected Mbeya to be now the fourth largest city in Tanzania with a population of nearly 150 000. As a result, both Mbeya's electricity sector and urban infrastructure remain relatively underdeveloped for a city of its size and economic important. The railway changed the nature of the city, much as it changed the nature of Shinyanga more than 40 years previously. The lesson is that if urban growth occurs in unexpected areas, investment must be made to keep pace with this growth if the city is not to become a large village with little infrastructure and few services. The eco-

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nomic, social and environmental costs of allowing investment-poor urban developments to grow are likely to be far greater than the investment in infrastructure and services necessary to make the cities habitable. Dramatic reductions of urban growth to smaller urban areas is more likely during historical periods when the government is heavily involved in planning economic activities and building infrastructure. The current epoch in Tanzanian history would appear to be one favouring private, not public sector, economic initiatives. As a result, urban and industrial growth is more likely to be directed to the existing large urban centres which demonstrate favourable market locations, leaving a smaller chance of dramatic leapfrogging of cities up the urban hierarchy.

Conclusions One important characteristic of the process of urbanization is energy intensification, or the increasing intensity of energy used per capita. This intensification is attributable to greater energy consumption in the industrial, commercial and transport sectors of the local economy, and to a shift towards modern fuels in the household sector. If the pace of economic and industrial growth slackens, then so does the rate at which energy consumption per capita increases and at which commercial fuels substitute for traditional fuels. For global energy planners, the increasing use of petroleum fuels means that developing country cities will demonstrate an increasingly large contribution to global carbon emissions. The implications are also important for national energy planners: the increased needs of urban dwellers and businesses for petroleum and electricity will have to be catered and planned for. Particularly as local forest resources are unlikely to remain sufficient to meet future household energy needs, plans to substitute and supply modern fuels will have to be initiated in all types of cities. The natural process of urban diffusion is down the urban hierarchy: innovations are first adopted in larger cities before arriving at smaller cities and towns. In the case of improved efficiency charcoal stoves, the research elaborated in this paper would indicate that the smallest cities are presently in the greatest need of such stoves. Energy planners should focus stove programmes upon the dissemination to these smaller towns instead of allowing the natural process of trickle down diffusion to determine which cities discover and adopt these energy innovations first. Finally, the results of this comparative analysis demonstrate that energy planners will have to begin

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Urban energy systems in Tanzania to allow for different energy needs for cities of d i f f e r e n t sizes a n d d i f f e r e n t l e v e l s o f t h e u r b a n h i e r a r c h y . J u s t as all cities a r e n o t i d e n t i c a l , n e i t h e r should their energy consumption patterns be exp e c t e d to b e i d e n t i c a l . M u c h o f this d i f f e r e n t i a t i o n will p r o b a b l y d i s a p p e a r w i t h c o n t i n u e d i n d u s t r i a l i z a t i o n a n d d e v e l o p m e n t as l o c a l e c o l o g y a n d h i s t o r y come to be dominated by market forces and industrial n e e d s . A l l cities will e v e n t u a l l y b e c o m e u n i f o r m ly d e p e n d e n t u p o n e l e c t r i c i t y a n d p e t r o l e u m , w i t h t h e o n l y d i f f e r e n c e s b e i n g v a r i a t i o n s in q u a n t i t y . B u t u n t i l this l e v e l o f d e v e l o p m e n t is a c h i e v e d , e n e r g y planners and energy policy must allow for localized v a r i a t i o n s in f u e l m i x e s a n d q u a n t i t i e s by c i t i e s w i t h d i f f e r e n t sizes a n d u r b a n f u n c t i o n s . T h e y will also h a v e to a c k n o w l e d g e t h a t t h e i n c r e a s i n g d e m a n d f o r modern fuels on the part of urban firms and househ o l d s will h a v e to b e m e t o r a l t e r e d t h r o u g h c o n servation activities. The economic, social and env i r o n m e n t a l c o n s e q u e n c e s o f f a i l i n g to i n v e s t a d e q u a t e l y in t h e n e e d e d e n e r g y s u p p l i e s will b e d e t r i m e n t a l f o r h o u s e h o l d s , i n d u s t r i e s a n d b u s i n e s s in all u r b a n a r e a s .

The author would like to thank Charlie Heaps, Don Jones, Michael Lazarus and Tom Wilbanks for helpful comments received on an earlier draft of this paper. The final contents remain the sole responsibility of the author. aGraham Connah, African Civilizations: Precolonial Cities and States in Tropical Africa: An Archaeological Perspective, Cambridge University Press, New York, 1987. 2Allen C. Kelley and Jeffrey G. Williamson, What Drives Third World City Growth? A Dynamic General Equilibrium Approach, Princeton University Press, Princeton, 1984. 3Arguably, the worst urban environment in the world is found in Mexico City, where a population of nearly 20 million live under some of the worst environmental conditions in the world. Lack of water resources and extreme air pollution have combined with limited access to technology to make Mexico City one of the few examples of a city facing true diseconomies of scale. 4The literature on the costs of urbanization is presented in Johannes F. Linn, 'The costs of urbanization in developing countries', Economic Development and Cultural Change, Vol 30, No 3, 1982, pp 625-648; and Harry W. Richardson, 'The costs of urbanization: a four-country comparison', Economic Development and Cultural Change, Vol 35, No 3, 1987, pp 561-580. 5The idea of ruralization or villagization of African cities is drawn from the discussion in Richard Stren, 'The ruralization of African cities: learning to live with poverty', in R. Stren and C. Letemendia, eds, Coping With Rapid Urban Growth in Africa: An Annotated Bibliography, Centre for Developing-Area Studies, Bibliography Series No 12, McGill University, Montreal, 1986. 6R.H. Hosier, 'Urban development and resource management: a brief history of three Tanzanian cities', Stockholm Environment Institute, Stockholm, 1993 (abstract in this issue of Energy Policy). 7For general discussions of the ecology of cities see Anne Whyte, 'Ecological approaches to urban systems: retrospect and prospect', Nature and Resources, Vol 21, No 1, 1985, pp 13-20 and Ariel Lugo, 'Cities in the sustainable development of tropical landscapes', Nature and Resources, Vol 27, No 2, 1991, pp 27-35.

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8Ken Newcombe, Jetse D. Kalma and Alan R. Aston, 'The metabolism of a city: the case of Hong Kong', Ambio, Vol 7, 1978, pp 3-15; Matthew V. Milukas, Energy Flow in a Secondary City: A Case Study of Nakuru, Kenya, unpublished PhD dissertation, Department of Geography, University of California, Berkeley, 1987; on Dhaka, Richard L. Meier and A.S.M. Abdul Quium, 'A sustainable state for urban life in poor societies: Bangladesh', Futures, March 1991, pp 128-145; and on Jakarta, Richard L. Meier, 'A stable urban ecosystem', Science, No 192, 1976, pp 962-968. 9Donald W. Jones, 'How urbanization affects energy-use in developing countries', Energy Policy, Vol 19, September 1991, pp 621-630. 1°Susan Owens, Energy, Planning, and Urban Form, Pion, London, 1986. ~lFor the individual analysis of each subsector, see the subsector working papers. ~2The Long-range Energy Alternatives Planning System (LEAP) was utilized for developing the energy balances and the scenarios developed for this analysis. Able assistance from Mike Lazarus and Charlie Heaps of the SEI-Boston office and Bashiri Mrindoko of the Ministry of Water, Energy, and Minerals helped make this undertaking possible. 13As noted earlier, there may be some inaccuracies in the allocation of liquid fuels to cities as the control totals used provide only the quantity of each product distributed to the region. As a result, the quantity of petrol, diesel and kerosene estimated as being consumed within the city is probably exaggerated, as much of the fuel is undoubtedly purchased within city limits and consumed in the rural areas. In Mbeya and Shinyanga, for example, perhaps as little as 40% of the quantity of kerosene listed is actually consumed within city limits. ~4Although generic efficiencies can be misleading, they can be used for the sake of simple comparisons. Basically, they highlight the inefficiency of traditional fuel use. Generic efficiencies are electricity 60%; liquid fuels 30%, charcoal 20%, and fuelwood and other traditional fuels 10%. They are derived from G. Leach and M. Gowen, Household Energy Handbook, World Bank Energy Sector Management Assessment Program, Washington, DC, 1987. When they are applied to the energy-use information in Table 1, the average inhabitant of Dares Salaam accounts for the consumption of 4.50 useful GJ of energy; a Mbeya inhabitant accounts for 5.32 useful G J; a Shinyanga dweller accounts for 3.71 useful GJ of energy; and a rural dweller, only 2.38 useful GJ per energy. The national average for 1990 is estimated at 2.94 GJ per capita. ~SThe biggest difference is accounted for by the fact that the process of converting wood to charcoal is estimated to be 22% efficient. It should also be noted that the electricity demands of Mbeya and Shinyanga are small enough to be met through conventional thermal generation. Only Dares Salaam's electricity requirements are great enough to require the generation from Tanzania's hydro plants. This explains why hydro appears only in the histogram of D a r e s Salaam. In addition, the conversion efficiency of hydro is assumed to be 100%, according to the convention used within the LEAP system. This differs from other energy balance systems in which the conversion efficiency of hydro is assumed to be equivalent to that achieved by thermal process, roughly 33%. For a worthwhile discussion, see J. Dunkerley, 'Energy balances explained', in W. Ramsay, Bioenergy Planning in Developing Countries, Westview Press, Boulder, CO, 1985. ~6The economic costs of fuel use are utilized instead of the resource costs as the prices of the resources are not easily estimated, whereas the prices of the fuels are. The economic prices for the different fuels are taken from R.H. Hosier and W. Kipondya, 'Urban household energy use in Tanzania: prices, substitutes and poverty', in this issue of Energy Policy. 17The per capita measures are used for comparative purposes (ie to control for city size), and should not be allowed to confuse the issue of who the actual users of the fuels and resources are. The term users in this context refers in the broadest sense to the end

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Urban energy systems in Tanzania users of the energy, not just the average resident, referred to only for comparative purposes. The energy bill of any individual resident covers only those fuels actually consumed by each individual. For the economic costs, however, the argument could well be made that someone or something must meet the full average costs of the energy supplies utilized. For example, in the case of woodfuel, the full economic cost is met through a deterioration of forest resources as there is no guarantee that the woodfuel is produced sustainably. 18However, they gloss over the strong similarities between the sectoral breakdowns in D a r e s Salaam and Mbeya. Only in the case of the commercial and urban-service sector does a notable difference between the subsectoral difference arise between the shares devoted to the two subsectors in each city. tgThe rural industrial category was taken from other sources and was not verified as part of this study. It is possible, therefore, that it is an overestimate. Whatever the case, it consists solely of firewood consumption, so that it is more comparable to the industries interviewed as part of the informal sector study, rather than the formal industrial sector work. 2°There has been no attempt to account for rural-urban transport in the existing energy accounts, which makes the rural consumption of transport fuels (gasoline and diesel) seem insignificant. 2tMbeya's electricity network is probably underdeveloped and Shinyanga's electricity network is overdeveloped. The latter can be attributed to the presence of Williamson Diamond mines or Mwadui nearby, which supplied Shinyanga with power before it

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was connected to the grid. The former can be attributable to the weak infrastructure found in Mbeya generally. Income differentials would appear to play no role as household incomes were estimated to be highest in Mbeya, next highest in Dares Salaam, and lowest in Shinyanga: see op cit, Ref 16. 22The difficulty of pumping water into D a r e s Salaam is probably more of a scale effect, while that of providing water to Shinyanga is more of a local ecological effect. 23For more discussion of these woodlots, see R.H. Hosier, 'Charcoal production and environmental degradation: environmental history, selective harvesting and post-harvest management', in this issue of Energy Policy, and op cit, Ref 6. 24R. Hosier, J. Boberg, M. Luhanga and M.J. Mwandosya, 'Energy planning and wood balances: sustainable energy future for Tanzania', Natural Resources Forum, Vol 14, No 2, 1990, pp 143-154, 25j. Boberg, 'Competition in Tanzanian woodfuel markets', in this issue of Energy Policy. 26Any discussion of urban economies of scale can only be tentative at best with a sample of three points. The suggestion that Mbeya might be experiencing diseconomies of scale might change dramatically if the large quantity of petroleum fuels going to T A Z A R A is segmented off into interurban and rural-urban end uses. However, the observation that Mbeya has an underdeveloped infrastructure is valid, given the reasons advanced in the text. 270p cit, Ref 8, Milukas.

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